Enter any address in Lyman County, South Dakota to see its FEMA flood zone
Flash flooding from summer thunderstorms is the dominant flood character in Lyman County. Between 2000 and 2023, NOAA Storm Events data recorded 26 flood events and 12 flash flood events, the latter resulting in two fatalities. For example, scattered thunderstorms on August 3, 2023, produced heavy rainfall causing flash flooding with water reported flowing over roads in West Brule. More recently, on June 20, 2024, thunderstorms with heavy rainfall led to significant accumulations, with one station near Oacoma recording 7.46 inches of rain.
National Flood Insurance Program (NFIP) claims data indicates that properties in Zone A have experienced 11 claims with an average payout of $5,059 and an average water depth of 2.1 feet. Zone D, though less frequent with 2 claims, has shown higher average payouts of $113,113 and an average water depth of 4.5 feet. Residents in low-lying areas, particularly those near creeks and rivers, and properties located in mapped flood zones should pay close attention to flood risk.
Summary generated from NOAA storm narratives and NFIP claim data for this county. Not predictive.
10 NOAA storm reports from this county describe what happened, in the words of the meteorologists who were there.
Lyman County, South Dakota has recorded 38 flood-related events since 1996 according to NOAA's Storm Events Database, including 12 flash floods and 26 river or area floods. The county has received 30 federal disaster declarations, 8 of which involved flooding or coastal storms. Enter any address above to check its FEMA flood zone designation.
FEMA Disaster Declarations (1976–2020)
Source: OpenFEMA Disaster Declarations Summaries.
| Declaration | Type | Date |
|---|---|---|
| Covid-19 | Biological | Jan 20, 2020 |
| Covid-19 Pandemic | Biological | Jan 20, 2020 |
| Severe Storms And Flooding | Flood | May 21, 2019 |
| Severe Winter Storm, Snowstorm, And Flooding | Flood | Mar 13, 2019 |
| Severe Storms, Tornadoes, Straight-line Winds, And Flooding | Severe Storm | Jun 17, 2015 |
| Flooding | Flood | Mar 11, 2011 |
| Flooding | Flood | Mar 10, 2010 |
| Severe Winter Storm And Snowstorm | Severe Storm | Dec 23, 2009 |
| Severe Storms And Flooding | Severe Storm | Jun 2, 2008 |
| Hurricane Katrina Evacuation | Coastal Storm | Sep 6, 2005 |
NOAA Storm Events Database (1996–2025)
Source: NOAA National Weather Service Storm Events Database.
| Type | Date | Damage |
|---|---|---|
| Flash Flood | Aug 3, 2025 | 0.00K |
| Flash Flood | Jun 20, 2024 | 0.00K |
| Flood | Feb 8, 2024 | 0.00K |
| Flood | Oct 13, 2023 | 0.00K |
| Flood | May 26, 2019 | 0.00K |
| Flood | Mar 26, 2019 | 0.00K |
| Flood | May 22, 2019 | 0.00K |
| Flood | Mar 14, 2019 | 0.00K |
| Flash Flood | Aug 2, 2019 | 0.00K |
| Flood | May 1, 2019 | 0.00K |
Flash Flood — Aug 3, 2025
Scattered thunderstorms on the afternoon of August 3rd produced large hail and caused flash flooding in Lyman County. Heavy rainfall from these storms led to a trained spotter reporting water flowing over roads in West Brule.
Flash Flood — Jun 20, 2024
Thunderstorms with heavy rainfall produced flooding across a broad swath of Lyman, Buffalo and Hand counties. In Lyman county, 7.46 inches was observed at a weather station 6 miles south southwest of Oacoma, while the South Dakota State University mesonet station near Oacoma recorded 5.51 inches. A CoCoRaHS observer 5 miles west southwest of Oacoma also observed 4.79 inches. In nearby Buffalo c...
Flood — Feb 8, 2024
Above normal temperatures resulted in rapid snow melt across central South Dakota. This snow melt resulted in a rise in river levels of Medicine Creek which lasted for about a day before steadily receding. A peak crest of 1667.53 was observed on the morning of 2/9, with only minor rural flooding.
Flood — Oct 13, 2023
The Cedar Creek near Presho briefly rose above the 12 foot flood stage during the morning of October 13th. The flooding was caused by 3 to 5 inches of heavy rainfall. The creek crested at 12.36 feet during the mid morning hours before falling below flood stage at 1:30 PM CDT. The flood waters impacted low-lying pasture lands.
Flood — May 26, 2019
A series of disturbances associated with a persistent area of low pressure over the western half of the U.S. produced several rounds of heavy rain. This rainfall, coupled with saturated soils from a wet early spring and flooding over the previous week, led to more flooding on the White River.
Source: NOAA National Weather Service Storm Events Database.
Source: OpenFEMA NFIP Individual Claims (2.25M records analyzed).
FEMA assigns flood zone designations to areas in Lyman County, South Dakota:
AE High Risk — 1% annual chance of flooding. Insurance required.
VE Very High Risk — Coastal flooding with wave action.
X (Shaded) Moderate Risk — 500-year floodplain.
X Low Risk — Outside major floodplains.
Properties in Lyman County, South Dakota that are in FEMA-designated Special Flood Hazard Areas (zones A and V) with federally backed mortgages are required to carry flood insurance.
Even outside high-risk zones, flood insurance is recommended. From 2014 to 2024, nearly one-third of NFIP claims came from outside the high-risk Special Flood Hazard Area.
Visit FloodSmart.gov to find an agent and get a quote.